The objectives of the proposed study are to advance Type 2 translational science through an effectiveness-implementation type 2 hybrid design to evaluate the clinical and cost-effectiveness of an efficacious intervention (Teen Marijuana Check-Up, TMCU) and compare the feasibility, acceptability, impact and cost-effectiveness of two integrity monitoring support systems. Marijuana continues to be the most frequently used drug in the U.S. and adolescent use is associated with negative effects such as academic failure, dropout, and emotional problems. Although marijuana is the most common presenting substance for 12-17 year olds seeking substance abuse treatment, few voluntarily seek indicated services. The TMCU is a brief, school-based motivational enhancement therapy approach that has been systematically evaluated in three randomized controlled trials with reliable beneficial effects in prompting voluntary participation in the intervention and decreasing adolescent marijuana use. With TMCU now well-positioned for broad dissemination, its public health impact may be enhanced by further research addressing: 1) to what extent its documented efficacy under controlled conditions translates to real-world effectiveness, and 2) what support systems are most useful in promoting sustained integrity in its delivery by the available school-based personnel. The proposed type 2 effectiveness/implementation hybrid trial will include randomization at multiple levels. Students will be randomly-assigned in a 1:2 ratio to `services-as-usual' and TMCU intervention conditions, and school-based personnel identified to deliver TMCU will be randomly-assigned to do so under governance of a `gold-standard' training/oversight support system (i.e., rapid, continual performance-based feedback and weekly coaching about integrity of TMCU delivery) or a less resource-intensive support system similarly including performance-based feedback but with process benchmarking (defined by prior performance of research interventionists in TMCU efficacy trials) prompting points at which these school-based personnel receive purveyor coaching. Expected trial participation of ten schools will enable recruitment of 30 TMCU interventionists, and access to a pool of 250 marijuana-using students during a two-year implementation period. This nested design (e.g., students in schools/intervention conditions; interventionists in schools/training/oversight support systems) will utilize multilevel models in study analyses to account for possible school-level clustering. A cost analysis will also be conducted. Longitudinal outcome and process data will be collected from school based staff (6, 12, 18, & 24 month follow-ups) and students (3 and 6 month follow- ups). The trial will occur in Washington state at an opportune time when legislative, fiscal, and socio-cultural factors converge to heighten potential adolescent exposure to marijuana-related harms-represents an effort by this investigative team to respond to such local challenges in a manner that will advance understanding of best practices for dissemination and implementation of this and other efficacious, school-based interventions.